In recent years, an electric vehicle has a very good prospect and becomes the trend of industrial development because it can reduce greenhouse gas emissions, promote sustainable energy development and improve air quality. A power battery pack is responsible for storing and supplying electric energy and is a core part of the electric vehicle.
A Battery Management System (BMS) is an important link for connecting the power battery pack to the electric vehicle. The BMS plays a very important role in extending a service life of the power battery pack and maintaining the performance of the power battery pack.
During a charging or discharging process of the power battery pack, the State of Charge (SOC) of the power battery pack is an important parameter in the control of the electric vehicle. A calculation precision of the SOC will directly affect the mileage and service life of the electric vehicle. Therefore, the BMS needs to accurately estimate the SOC of the power battery pack.
The SOC of the power battery pack can be calculated by an ampere-hour integration method. This method of calculating the SOC may detect a current value of the power battery pack in real time and make a cumulative calculation with a specific algorithm, so as to measure the SOC of the power battery pack according to a cumulative result during a period of time. Therefore, the accuracy of the current detection for the power battery pack will directly affect the calculation result of the SOC.
Generally, the current value of the power battery pack can be acquired by a shunt-type current sensor. However, when the shunt-type current sensor fails, the current value of the power battery pack cannot be acquired and the cause of the fault cannot be determined, which results in a low reliability of the current detection.